Methods and devices for semi-rigid bone fixation

ABSTRACT

Apparatus and methods are provided for the approximation of two bones, the apparatus including a first anchor that is rotationally driven into a first bone by a second bone anchor, which receives driving torque from a driver tool. After the first anchor is secured in the first bone, the second anchor is disengaged from the first anchor but remains connected to the first anchor by a flexible link of a designed length. The second bone anchor is secured in the second bone and has provisions to be lengthened or shortened to adjust the overall length of the implant, thereby adjusting the approximation between the two bones.

RELATED APPLICATION DATA

The present application is a divisional of co-pending application Ser.No. 15/045,224, filed Feb. 16, 2016, issuing as U.S. Pat. No.10,327,826, which claims benefit of provisional application Ser. No.62/116,852, filed Feb. 16, 2015, the entire disclosures of which areexpressly incorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to apparatus and methods for semi-rigidfixation of bones. More specifically, certain embodiments relate tosystems and methods for fixation of the distal tibia and distal fibulafollowing an injury to the corresponding syndesmotic joint.

BACKGROUND

A syndesmotic injury results when a traumatic injury damages theligaments that span the gap between the distal tibia and fibula. Thiscan be the result of a high ankle sprain, with no fracture of thefibula, or can also accompany a fibular fracture in a Weber B or Weber Cfracture.

A surgeon can determine the presence of a syndesmotic injury by directvisualization of the joint or through radiographic imaging whilepositioning the ankle in a mortise view orientation. In either case,loads are applied to the joint in either a direct lateral load appliedto the fibula or by applying an external rotation load to the foot.While the load is being applied, the relative distance between thefibula and the tibia, the fibula and the talus, and the tibia and thetalus are observed to determine the level of damage sustained by theligaments that typically hold the syndesmotic joint together.

If a syndesmotic injury is found to be present, the typical treatmentinvolves stabilizing the fibula and tibia with respect to each other inthe proper orientation and holding them there throughout the soft tissuehealing period to allow the ligaments to re-attach and heal. In theevent of a syndesmotic injury with a corresponding fibula fracture, thisis done while also stabilizing the fibular fracture, which is usuallyaccomplished with a small fracture plate on the lateral side of thefibula. Traditionally the method of stabilization has been to place oneor more cortical screws across the syndesmosis, with the head againstthe lateral face of the fibula and the tip of the screw being in themiddle of the tibia or in the medial cortex of the tibia, e.g., as shownin FIG. 1.

This form of treatment provides very rigid fixation, allowing theligaments to heal, but makes return to weight-bearing more difficult.During a standard gait, the ligaments hold the distance between thetibia and fibula fairly constant, but allow a small amount of shearmotion and rotation of the fibula with respect to the tibia. Thepresence of the fixation screws prevents this motion and can causediscomfort and limited flexibility of the ankle joint. Typically, thesurgeon prescribes a secondary surgery to remove the screws once theligaments have healed. In some cases, a surgeon may simply recommend areturn to weight-bearing when the ligaments have healed and, after aperiod of time of loading the screws, they will experience a fatiguefailure and normal anatomical motion will be restored.

Accordingly, apparatus and methods for providing semi-rigid fixation ofthe distal tibia and fibula following a syndesmotic injury would beuseful.

SUMMARY

The present invention is directed to apparatus and methods forstabilizing a joint between two bones, e.g., during the soft tissuehealing period following a traumatic injury.

In an exemplary application, the apparatus and methods herein may beconfigured to provide substantially rigid tensile fixation between thetibia and fibula while allowing the small amount of shear and rotationalmotion required for a standard gait. This may make it possible forpatients to return to weight-bearing earlier, which may improve clinicaloutcomes, and/or may also reduce the number of follow-uphardware-removal surgeries.

In accordance with one embodiment, an apparatus is provided for placinga first anchor in a first bone such as a tibia, a second anchor in asecond bone such as a fibula, the two anchors being connected by aflexible member that provides substantial tensile stabilization butoffers little or no resistance to bending, rotation, or shear motion ofthe two anchors with respect to each other. In this embodiment, thefirst anchor may have an external threadform allowing it to be advancedcompletely into the tibia leaving no rigid hardware in the joint space.Further, the second anchor may include a distal piece and a proximalpiece, the distal piece of which has an external threadform mated to aninternal threadform in the proximal piece, allowing precise adjustmentof the overall length of the construct and therefore the amount oftensile compression applied to the joint.

In accordance with another embodiment, a method is provided fordelivering this system in which a driver is used to impart the torquerequired to install the first anchor into the first bone. This torque isnot applied directly to the first anchor, but is applied through thedistal piece of the second anchor, which is coupled to the first anchorduring the early deployment steps. Once the first anchor is properlyplaced, this coupling is released by the surgeon, and the distal pieceof the second anchor is allowed to disengage and retract to its positionin the second bone. Rotation of this distal piece of the second anchoris controlled by another installation tool while the proximal piece iscoupled to it and adjusted to the desired position. This desiredposition is infinitely adjustable and should result in the proper amountof joint correction. Once the desired position is reached, allinstallation tools are released and withdrawn by the surgeon, leavingonly the implant construct.

In accordance with still another embodiment, an apparatus is providedfor that has a first anchor with features other than an externalthreadform to attach it to the first bone. In exemplary embodiments,these features may include barbs or wings that are deployed by thesurgeon. In the same way, the coupling between the distal and proximalpieces of the second anchor may be accomplished using features otherthan a threadform. In exemplary embodiments, these features may includea ratchet and pawl mechanism or a friction fit that may be tightened bythe surgeon when the proper placement is reached.

In accordance with yet another embodiment, an apparatus is provided forthe approximation of two bones that includes a first anchor comprising aproximal end, a distal end configured for insertion into a first bone,and a bore extending from the proximal end towards the distal end, thebore including a proximal region defining a plurality of walls, and anintermediate region distal to the proximal region including a firstmount, and a second anchor. The second anchor includes a first componentincluding a proximal end, a distal end sized to be inserted into theproximal region of the bore in a delivery configuration and having apredetermined shape such that the distal end engages the plurality ofwalls in the delivery configuration to transfer torque or other forcesfrom a driver tool coupled to the first component to the first anchor,and a second mount; a second component including a tubular body sized tobe advanced over the first component proximal end and including one ormore features for cooperating with one or more corresponding features onthe first component to control advancement of the second component overthe first component, and an enlarged head on a proximal end of thetubular body; and a flexible link extending between the first and secondmounts for limiting spacing of the first component from the first anchorwhen the first component distal end is disengaged from the proximalregion of the bore in a deployed configuration.

In accordance with another embodiment, a system is provided for theapproximation of first and second bones that includes a first drivertool comprising a proximal end, a distal end, a lumen extending betweenthe driver tool proximal and distal ends, and a socket in the distalend; a guide member slidably inserted into the first driver tool lumenand including a distal end including one or more connectors disposedadjacent the first driver tool distal end; and an implant. The implantincludes a first anchor comprising a proximal end, a distal endconfigured for insertion into a first bone, and a bore extending fromthe proximal end towards the distal end, and an intermediate regiondistal to the proximal region including a first mount; a first componentfor a second anchor comprising a proximal end received in the socket ofthe first driver tool, a distal end extending from the first driver tooldistal end and received in the proximal region of the bore and shaped toengage the first anchor to transfer torque or other forces from thefirst driver tool to the first anchor to insert the first anchor into afirst bone, a second mount adjacent the distal end, and one or moremating connectors engaged with the one or more connectors of the guidemember; a second component for the second anchor including a tubularbody sized to be advanced over the first component proximal end when thefirst driver tool is removed after inserting the first anchor into boneto expose the proximal end of the first component, and an enlarged headon a proximal end of the tubular body, the tubular body including one ormore features for cooperating with one or more corresponding features onthe first component to control advancement of the second component overthe first component; and a flexible link extending between the first andsecond mounts for limiting spacing of the first component from the firstanchor when the first component distal end is disengaged from theproximal region of the bore. Optionally, the system may also include asecond installation tool engageable with the head of the secondcomponent for directing the second component over the first component toadjust an overall length of the implant, thereby adjusting theapproximation between the first and second bones.

In accordance with still another embodiment, a method is provided forapproximating first and second bones relative to one another thatincludes advancing a first anchor into a first bone by applying a torqueor other force to a driver tool coupled to a first component of a secondanchor, the first component coupled to the first anchor; disengaging thefirst component of the second anchor from the first anchor to expose aflexible link extending between the first anchor and the first componentof the second anchor; withdrawing the second anchor until the flexiblelink connecting the two reaches its designed length, thereby positioningthe second anchor in a second bone; affixing a second component of thesecond anchor to the first component of the second anchor such that ahead of the second component engages the second bone or a bone supporton the second bone; and adjusting a location of the second componentalong the first component to adjust the approximation between the firstand second bones.

In accordance with yet another embodiment, a method is provided forapproximating first and second bones relative to one another thatincludes providing a driver tool including a shaft having a distal end,a first anchor, a first component of a second anchor including a distalend received in a first socket of the first anchor, and a proximal endreceived in a second socket in the driver tool shaft distal end, and aguide member coupled to the first component proximal end and extendingproximally through the driver tool shaft, the first anchor and firstcomponent secured relative to the driver tool shaft distal end;advancing the first anchor towards a first bone through a hole in asecond bone adjacent the first bone; applying a torque or other force tothe driver tool to direct the first anchor into the first bone, theforce transferred from the driver tool shaft to the first anchor via thefirst component of the second anchor; releasing the first anchor andfirst component from the driver tool shaft distal end; withdrawing thedriver tool, thereby exposing the guide member; directing a secondcomponent of the second anchor over the guide member to the firstcomponent; advancing the second component of the second anchor over thefirst component, thereby causing the first component distal end towithdraw from the first socket and expose a flexible link extendingbetween the first anchor and the first component of the second anchor;advancing the second component further, thereby extending the flexiblelink to a predetermined or designed length and positioning the secondanchor in the hole in the second bone; engaging a head of the secondcomponent with the second bone or a bone support on the second bone; andadjusting a location of the second component along the first componentto adjust the approximation between the first and second bones.

Other aspects and features of the present invention will become apparentfrom consideration of the following description taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate exemplary embodiments of the invention, inwhich:

FIG. 1 is a mortise view of an ankle joint showing fixation withcortical screws.

FIG. 2 is a perspective view of an exemplary embodiment of an implantfor providing semi-rigid fixation between two bones.

FIG. 3 is a cross-sectional view of the implant of FIG. 2 as installedin a tibia and fibula.

FIG. 4 shows an exemplary embodiment of an entire kit, including animplant, such as that shown in FIG. 2, and its delivery tools.

FIGS. 5-14 are cross-sectional views of a tibia and fibula showing anexemplary method for installing an implant, such as that shown in FIG.2.

FIG. 5 is a depiction of a K-wire and step-drill being used to preparethe implant site.

FIG. 6 shows a first anchor being placed in the tibia using a firstanchor driver tool.

FIG. 7A shows a suture on a handle of the first anchor driver tool thatkeeps the first anchor driver tool, the distal piece of the secondanchor, and the first anchor engaged.

FIG. 7B shows the suture being released to release the first and secondanchors from the first anchor tool driver.

FIG. 8 shows the first anchor driver tool being retracted, exposing adistal component of the second anchor and guide tube that is coupled tothe second anchor to control its motion.

FIG. 9 is a detail showing the engagement of the distal component of thesecond anchor with the guide tube and the first anchor.

FIG. 10A shows the proximal component of the second anchor beingdirected over the guide tube using a second anchor installation tool,and engaging a back end of the first anchor driver tool with the guidetube.

FIG. 10B is a detail showing the first anchor driver tool being engagedwith the guide tube to control the motion of the guide tube.

FIG. 11 shows the proximal component of the second anchor being threadedover the distal component, thereby causing the distal component todisengage from the first anchor and exposing a flexible link between thetwo anchors.

FIG. 12 shows the guide tube being removed after the proximal componentis tightened to a desired position and implant placement is finalized.

FIG. 13 shows the second anchor installation tool being disengaged fromthe proximal component of the second anchor and withdrawn.

FIG. 14 shows the implant in its completely-installed state.

FIG. 15 is a cross-sectional view of the first anchor, distal componentof the second anchor, flexible link, and the guide tube as they arehoused in the first anchor driver tool.

FIG. 16 is a detail of the drive interface with which the first anchordriver tool imparts torque to the distal piece of the second anchor,which in turn imparts torque to the first anchor.

FIGS. 17A-17E are various details of exemplary connectors on the distalcomponent of the second anchor and the guide tube for releasablysecuring the distal component to the guide tube.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Turning to the drawings, FIGS. 2 and 3 show an exemplary embodiment of adevice or implant 8 for providing semi-rigid fixation between two bonesthat generally includes a first anchor 10 configured for insertion intoa first bone, e.g., a tibia 90 (shown in FIG. 3), a second anchor 18 forengaging a second bone adjacent the first bone, e.g., a fibula 92 (shownin FIG. 3), and a flexible link 20 extending between the first andsecond anchors 10, 18, e.g., to provide approximation between the firstand second bones 90, 92. The second anchor 18 generally includes a firstor distal component 30 coupled to the first anchor 10 by the flexiblelink 20 and a second or proximal component 40 configured to be threadedover the first component 30 for engaging the second bone 92. Optionally,one or more tools and/or accessories may also be provided, e.g., toprovide a system or kit for installing the implant 8. For example, asshown in FIG. 4, a system 6 may be provided that includes a first drivertool 50 for inserting the first anchor 10 into bone and a secondinstallation tool 70 for advancing the second component 40 of the secondanchor 18 over the first component 30. Optionally, the system 6 may alsoinclude a length of Kirschner wire 80, a custom step drill 82, and/or awasher 84, as described elsewhere herein.

Returning to FIGS. 2 and 3, the first anchor 10 is a rigid elongatemember including a proximal end 10 a, a distal end 10 b configured forinsertion into a first bone and terminating at a distal tip 10 c, one ormore external threads 11 extending at least partially between theproximal and distal ends 10 a, 10 b, and a bore 12 extending from theproximal end 10 a at least partially towards the distal end 10 b,generally along a longitudinal axis 14 of the implant 8. In an exemplaryembodiment, best seen in FIG. 3, the bore 12 includes a proximal region12 a, an intermediate region 12 b distal to the proximal region 12 aincluding a first support structure 16 therein, and a distal region 12 cextending from the intermediate region 12 b to a recess 12 d in thedistal tip 10 c. The proximal region 12 a may include a plurality ofwalls, e.g., defining a polygonal shape, such as a triangular, square,pentagonal, hexagonal, octagonal shape, and the like, to provide asocket for receiving the first component 30 of the second anchor 18, asdescribed elsewhere herein. The intermediate region 12 b and distalregion 12 c may have a circular or other desired cross-sectional shape,with the distal region 12 c having a diameter or other maximumcross-section smaller than the intermediate region 12 b. The recess 12 dmay have a diameter or other cross-section larger than the distal region12 c, e.g., to receive a knot 20 c or otherwise fixed ends 20 a of theflexible link 20, as described elsewhere herein.

The first support structure 16 may be provided within the bore 12, e.g.,across the intermediate region 12 b substantially perpendicular to thelongitudinal axis 14. In an exemplary embodiment, holes 10 d may beprovided through opposite side walls of the first anchor 10 into theintermediate region 12 b and a pin 16 may be inserted into the holes 10d such that the pin 16 extends across the intermediate region 12 b andsubstantially permanently attached thereto, e.g., by one or more ofpress-fit or other interference fit, bonding with adhesive, sonicwelding, soldering, and the like. In an alternative embodiment, theholes 10 d may be omitted and a pin may be inserted through the proximalregion 12 a of the bore and positioned and fixed across the intermediateregion 12 b, e.g., by one or more of interference fit, bonding withadhesive, sonic welding, soldering, and the like. In anotheralternative, a support structure may be integrally formed with the firstanchor 10, e.g., machined, cast, molded, and the like from the samepiece of material as the rest of the first anchor 10. The pin or othersupport structure 16 generally has a diameter or other cross-sectionsmaller than the intermediate region 12 b such that the flexible link 20may be wrapped at least partially around the support structure 16, asdescribed further elsewhere herein.

The external threads 11 may extend from the proximal end 10 a helicallytowards the distal end 10 b, e.g., entirely to the distal tip 10 c orthe threads 11 may terminate before the distal tip 10 c, e.g., toprovide a smooth-walled, unthreaded distal tip (not shown). The threads11 may have a substantially uniform configuration along the threadedregion of the first anchor 10 or the threads 11 may be varied asdesired, e.g., having different heights, edges, and/or axial spacing(threads per millimeter), as desired.

Optionally, as can be seen in FIG. 3, the threads 11 may end before theproximal-most edge of the first anchor 10, e.g., about half to onemillimeter (0.5-1.0 mm). Such an offset may facilitate identifying theend of the first anchor 10, e.g., to identify the interface between thefirst anchor 10 and the first driver tool 50 (not shown, see FIG. 4). Inaddition, the offset may provide an unthreaded region on the proximalend 10 a in case the first anchor 10 extends a small distance from abone into which it is implanted, which may reduce risk of irritationand/or damage to adjacent tissue.

With continued reference to FIGS. 2 and 3, the first component 30 of thesecond anchor 18 is an elongate rod or tubular body including a proximalend 30 a, a distal end 30 b, and one or more external threads 32extending at least partially between the proximal and distal ends 30 a,30 b. In addition, the first component 30 may have an outer profile tofacilitate coupling the first component 30 between the first driver tool50 (not shown) and the first anchor 10. For example, as best seen inFIG. 2, the first component 30 may have a substantially uniformhexagonal outer profile along its length with the threads 32 conformingto the outer profile. The outer profile generally corresponds to thesize and shape of the proximal region 12 a of the bore 12 in the firstanchor 10, thereby allowing the distal end 30 b of the first component30 to be inserted into the proximal region 12 a. Similarly, the proximalend 30 a may have an outer profile corresponding to a lumen, recess, orother passage in the first driver tool 50 such that the proximal end 30a may be inserted into the first driver tool 50, e.g., as shown in FIG.4, thereby causing the first component 30 to transfer torque from thefirst driver tool 50 to the first anchor 10, as described furtherelsewhere herein. It will be appreciated that the proximal and distalends 30 a, 30 b may have similar profiles (e.g., the first component 30may have a substantially uniform shape along its length), or theproximal and distal ends 30 a, 30 b may have different shapes and/orsizes as long as they correspond to the size and shape of the sockets inthe first anchor 10 and first driver tool 50 that receive them.

In addition, as shown in FIG. 3, the first component 30 may include abore or passage 34 therein, e.g., extending partially or entirely fromthe proximal end 30 a to the distal end 30 b. The bore 34 may include aproximal region 34 a sized to receive a guide tube or member 60 (notshown, see, e.g., FIGS. 8 and 9) and including one or more pockets orother connectors 36 configured to engage corresponding connectors 66 onthe guide tube 60 (not shown, see, e.g., FIGS. 17A-17E), as describedelsewhere herein.

The first component 30 also includes a second mount or support structure38, e.g., adjacent the distal end 30 b for coupling the flexible link 20to the first component 30. In the exemplary embodiment shown, anaperture or passage 38 a is provided that extends through the firstcomponent 30 adjacent the distal end 30 b, e.g., through opposite sidewalls thereof substantially perpendicular to the longitudinal axis 14.The passage 38 a may have rounded surfaces and the like to accommodatewrapping a portion of the flexible link 20 through the passage 38 a andat least partially around the second mount 38.

In an exemplary embodiment, the flexible link 20 may be an elongatelength of suture or other filament having first and second ends 20 a.During assembly, one of the ends 20 a may be directed through thepassage 38 a until a central region 20 b is disposed around the secondmount 38, thereby defining a loop. The ends 20 a may then be directedinto the bore 12 of the first anchor 10, e.g., into the proximal region12 a, into the intermediate region 12 b, wrapped at least partiallyaround the first mount 16, and then into the distal region 12 c untilthe ends 20 a exit the bore 12 at the distal tip 12 d. The ends 12 a maythen be secured together, e.g., by tying one or more knots seated withinthe recess 12 d that have a cross-section larger than the distal region12 a, thereby preventing the ends 20 a from being pulled back throughthe bore 12 during implantation. Alternatively, one of the ends 20 a maybe directed through the bore 12 from the distal tip 10 c, wrapping theend at least partially around the first mount 16, exiting the proximalregion 12 a, wrapping the end 20 a around the second mount 38 and backthrough the bore 12 before tying the knot within the recess 12 d.

The knot of the ends 20 a may be tied to provide a predetermined lengthof suture from the ends 20 a to the loop 20 b around the second mount38, thereby providing a desired maximum spacing between the first anchor10 and the first component 30 of the second anchor 18, as describedelsewhere herein. For example, the length of the suture 20 may be setsuch that the maximum spacing between the proximal end 10 a of the firstanchor 10 and the distal end 30 b of the first component 30 may bebetween about two and four millimeters (2-4 mm).

In alternative embodiments, other configurations may be provided for theflexible link 20 to flexibly connect the first anchor 10 and the firstcomponent 30. For example, a central region of a suture may be wrappedaround the first mount 16 and the ends 20 a may be secured togetherwithin the first component 30, e.g. within a recess (not shown) in thedistal end 30 b beyond the second mount 38. In addition oralternatively, the ends 20 a may be secured together by one or more ofcrimping a sleeve (not shown) over the ends 20 a, fusing, bonding withadhesive, and the like in addition to or instead of knotting.

With continued reference to FIGS. 2 and 3, the second component 40 ofthe second anchor 18 generally includes an elongate tubular body 42including a proximal end 42 a, a distal end 42 b, and a passage 44extending at least partially from the distal end 42 b towards theproximal end 42 a. The passage 44 is sized to be advanced over theproximal end 30 a of the first component 30 and includes one or moreinternal threads 46 for cooperating with the external threads 32 on thefirst component 30, e.g., to allow the second component 40 to becontrollably advanced over the first component 30.

In addition, the second component 40 includes an enlarged head 48 on theproximal end 42 a, e.g., including a substantially flat or otherwiseshaped proximal surface 48 a and a flared or other expanding distalsurface 48 b, e.g. for engaging the second bone 92 as shown in FIG. 3.As shown in FIG. 3, the head 48 may include a connector or otherinterface 49 for engaging the second component 40 with the secondinstallation tool 70 (not shown, see, e.g., FIG. 4). For example, theconnector 49 may be a shaped recess including one or more pockets ordetents, and the second installation tool 70 may include correspondingconnector(s) 76 that may engage the connector 49 to secure the secondcomponent 40 to the second installation tool 70, yet allow the secondinstallation tool 70 to be disengaged when a predetermined force orother action is performed, as described elsewhere herein.

Optionally, the tubular body 42 may include one or more annular ridgesor other features 43 on an outer surface of the tubular body 42, e.g.,adjacent the proximal end 42 a. For example, the tubular body 42 mayhave an outer diameter smaller than a clearance hole drilled in bonethrough which the second component 40 is introduced, and the annularridges 43 may have a diameter similar to the clearance hole such thatridges 43 may contact surrounding bone to secure the tubular body 42within the bone, e.g., once bony ingrowth occurs.

Turning to FIG. 4, an exemplary embodiment of an entire kit is shownthat may be included in a system 6 for performing a procedure includingimplantation of an implant 8, such as that shown in FIG. 2. As shown,the kit generally includes a Kirschner wire 80 and a custom step drill82 for site preparation, the first anchor 10, e.g., optionally preloadedinto the first driver tool 50, which houses many of the other componentsduring the early phases of installation, and the second component 40 ofthe second anchor 18, e.g., optionally loaded onto the secondinstallation tool 70.

Optionally, a plurality of second components may be provided, e.g., theset of second components 40, 40′ shown in FIG. 4, that have differentdimensions such that an appropriate second component may be selectedbased on the individual patient anatomy encountered. For example, asshown, a standard second component 40 may be provided having a standardsize (i.e., length) and a large size second component 40′ may beprovided having a longer tubular body 42′ for situations when theinstalled implant construct needs to have a longer overall length. Inanother option, the system 6 may include a washer 84 included in thekit, which may be used in cases where the load of the second anchor 18needs to be spread out over a larger contact area of bone, such as inosteoporotic patients with poor bone quality.

As shown in FIG. 4, the first driver tool 50 generally includes anelongate tubular outer shaft 52 including a proximal end 52 a having ahandle 54 thereon, a distal end 52 b terminating in a distal tip 52 c,and a lumen (not shown) extending between the proximal and distal ends52 a, 52 b. The distal tip 52 c includes a recess or other socket (notshown) sized and/or shaped to receive the proximal end 30 b of the firstcomponent 30 of the second anchor 18, as described elsewhere herein.Optionally, the handle 54 includes one or more additional features,e.g., a cleating structure 58 and an actuator 59 for releasably securinga suture or other filament 56 used to secure the first anchor 10 and/orfirst component 30 to the first driver tool 50, as described elsewhereherein.

In addition, as shown in FIGS. 8-10B, the first driver tool 50 includesa guide tube or member 60 including an elongate inner shaft 62 sized toslidably fit within the lumen of the outer shaft 52, e.g., defining anouter diameter smaller than the inner diameter of the lumen of the outershaft 52. The inner shaft 62 includes a proximal end 62 a, a distal end62 b including one or more detents or other connectors 66 for securingthe first component 30 of the second anchor 18 to the guide tube 60, anda lumen 64 extending therebetween, e.g., for receiving a lock tube ormember 86.

For example, FIGS. 17A-17C show an exemplary embodiment of cooperatingconnectors 36, 66 that may be provided on the first component 30 and theguide tube 60. In the embodiment shown, the first component 30 includesthree pockets or holes 36 and the guide tube 60 includes threecorresponding fingers or connectors 66, although it will be appreciatedthat fewer (e.g., one or two) or more connectors 36, 66 may be provided,as desired. Each connector 66 includes a cantilevered arm 66 a and adetent 66 b carried on a free end of the arm 66 a. The arms 66 b may bebiased to an inward orientation, e.g., as shown in FIGS. 17B, 17D, and17E, yet may be directed outwardly, e.g., as shown in FIG. 17C, toengage the pockets 36. The guide tube 60 may also include stationaryarms 63, e.g., extending axially between each connector 66 such that thearms 63 may slide into the proximal region 34 a of the bore 34 in thefirst component 30.

During assembly, the distal end 62 b of the inner shaft 62 may beinserted into the proximal end 30 a of the first component 30, i.e.,with the connectors 66 in their inward orientation, as shown in FIGS.17D and 17E, and the detents 66 b may be aligned with respective pockets36 in the first component 30. Once properly positioned, the lock member86 may be inserted into the lumen 64 from the proximal end 62 a of theinner shaft 62 until a distal end of the lock member 86 (not shown) isinserted into the distal end 62 b and the connectors 66. The size of thelock member 86 may be such that its distal end slidably engages the arms66 a of the connectors 66, thereby directed them outwardly and insertingthe detents 66 b into the pockets 36, as best seen in FIG. 17C. Thus, inthis manner, the first component 30 cannot move axially and/or rotateabout the longitudinal axis 14 since it is coupled to the guide tube 60.

The outer shaft 52 of the first driver tool 50 may then be advanced overthe guide tube 60 until the distal 52 b is adjacent the first component30, whereupon the proximal end 30 a of the first component 30 may bereceived within the distal end 52 b of the outer shaft 52. The firstanchor 10 may then be inserted over the distal end 30 b of the firstcomponent 30 and the assembly secured, e.g., using the suture 56, asdescribed elsewhere herein. The first driver tool 50 may subsequently beprovided to an end user in this configuration, i.e., with the firstanchor 10 and first component 30 secured to the distal end 52 b of theouter shaft 52 and the guide tube 60 and locking member 86 inside theouter shaft 52.

Optionally, returning to FIGS. 10A and 10B, the proximal end 62 a of theinner shaft 62 may include one or more gripping features 63. Forexample, the gripping features 63 may include a plurality of holes,tabs, and the like that may be engaged by a tool to prevent movement ofthe guide tube while performing other operations, e.g., advancing thesecond component 40 of the second anchor 18 over the guide tube 60, asdescribed elsewhere herein. For example, as shown, the handle 54 of thefirst driver tool 50 may include a back end 54 a that includes areceptacle or other passage 55 sized to receive the proximal end 62 a ofthe guide tube 60. The back end 54 a may include a slot 54 b extendingaxially along the back end 54 a and radially inwardly to the receptacle55 such that the back end 54 a is compressible to reduce the size of thereceptacle 55. Thus, during use, the proximal end 62 a of the guide tube60 may be inserted into receptacle 55, whereupon the back end 54 a maybe squeezed or otherwise compressed to engage the guide tube 60 untilthe back end 54 a is released, as described elsewhere herein.

In addition, the first driver tool 50 includes one or more features forreleasably securing the first anchor 10 relative to the shaft 52. Forexample, as shown in FIGS. 7A and 7B, a suture or other filament 56 maybe provided that extends from the handle 54 through the lumen of theouter shaft 52 to the first anchor 10 and/or first component 30 wherethe suture 56 is looped around a portion of the flexible link 20, e.g.,between the first anchor 10 and the first component 30, first anchor 10and/or first component 30 where the suture 56 is looped around a portionof the flexible link 20, e.g., between the first anchor 10 and the firstcomponent 30, and returns back to the handle 54. This routing mayprovide a mechanical advantage and hold the first anchor 10 tightlyagainst the first component 30 and outer shaft 52. Alternatively, thesuture 56 may be looped around other components, e.g., the pin 16 withinthe first anchor, and returned to the handle. The suture 56 may betightened during assembly such that the first component 30 of the secondanchor 18 and the first anchor 10 are secured to the shaft 52 with thefirst component 30 received in the sockets of both the first anchor 10and the shaft 52, thereby holding the components to the first drivertool 50 during introduction, as described elsewhere herein. The ends 56a of the suture 56 may be secured to the handle 54 such that at leastone of the ends 56 a may be released when desired. For example, a firstend 56 a of the suture loop 56 may be secured through a cleatingstructure 58 on the handle 54 and the handle 54 may include an actuator59 that may activated to release the first end 56 a such that thenow-free first end 56 a retreats into the driver shaft 52 as the driveris withdrawn from the first anchor 10 to release the first anchor 10(and the first component 30) and allow subsequent separation.

Turning to FIGS. 5-14, an exemplary method is shown for installing theimplant 10 shown in FIGS. 2 and 3 between a tibia 90 and a fibula 92,e.g., using the system 6 shown in FIG. 4, to provide semi-rigid fixationof the bones relative to one another, e.g., to treat a syndesmoticinjury. It will be appreciated that the implants, systems, and methodsdescribed herein may also be used in other locations and/or procedures,e.g., to provide approximation between two bones other than the tibiaand fibula.

Initially, as shown in FIG. 5, the Kirschner wire may be placed throughthe fibula 92 and into the tibia 90 at the appropriate location, e.g.,using conventional methods, and then a drill may be introduced over theKirschner wire to create a hole 94 through the fibula 92 and at leastpartially into the tibia 90. In the exemplary embodiment shown in FIG.4, the drill may use a custom step drill bit 82 that includes arelatively smaller-diameter distal portion 82 a that creates a smallerpilot hole 96 in the tibia 90 and a relatively larger-diameter proximalportion 82 b creates a larger clearance hole 94 through the fibula 92.In an exemplary embodiment, the distal portion 82 a may be sized tocreate a pilot hole no larger than about three millimeters (3 mm) indiameter, and the proximal portion 82 b may be sized to create aclearance hole larger than four millimeters (4.0 mm), e.g., about 4.1mm, to accommodate a first anchor having an outer thread diameter offour millimeters (4.0 mm). It will be appreciated that other sizes maybe provided, as desired.

Turning to FIG. 6, the first anchor 10 may then be introduced throughthe clearance hole 94 and threaded into the tibia 90 via the pilot hole96 to a desired depth. For example, as described elsewhere herein, thefirst anchor 10 may be secured to the distal end 52 b of the outer shaft52 of the first driver tool 50 with the first component 30 (not shown)inserted into the first anchor 10 and outer shaft 52. Once the distaltip 10 c of the first anchor 10 engages the tibia 90, the first drivertool 50 may be rotated and advanced to thread the first anchor 10 intothe tibia 90 to a desired depth, e.g., such that the proximal end 10 aof the first anchor 10 is substantially flush with the outer surface ofthe tibia 90 (e.g., as best seen in FIG. 9). As can be seen, theclearance hole 94 drilled through the fibula 92 has sufficient size toaccommodate the outer shaft 52 of the first anchor driver tool 50passing therethrough to thread the first anchor 10 into the tibia 90.

Turning to FIGS. 7A and 7B, once the first anchor 10 is threaded intothe tibia 90 to the desired depth, the first driver tool 50 may beremoved. Since the first anchor 10 is secured to the outer shaft 52, theuser first releases the first anchor 4 from the first driver tool 50,e.g., by releasing the suture 56 from the cleat 58, and then the firstdriver tool 50 may be withdrawn, as shown in FIG. 7. As the first drivertool 50 is withdrawn, the free end 56 a of the suture 56 may retreatinto the handle 54 and outer shaft 52 until the suture 56 is disengagedfrom the flexible link 20 (or other structure around which the suture 56is looped).

As can be seen in FIG. 8, as the first anchor driver tool 15 is beingwithdrawn from its first anchor 10, the proximal end 30 a of the firstcomponent and the guide tube 60 are exposed.

FIG. 9 shows an exemplary embodiment of the interface between the firstanchor 10, the first component 30 of the second anchor 18, and the guidetube 60. In this close-up view, it can be seen that the first component30 of the second anchor 18 has an external profile capable of receivingdriving torque from the first anchor driver tool 50 and thentransmitting that torque to an internal feature of the same profile inthe proximal region of the first anchor 4. This close-up view also showsthe inter-locking connectors 36, 66 used to attach the guide tube 60 tothe first component 30 of the second anchor 18 until released by theuser.

Turning to FIGS. 10A and 10B, the second component 40 of the secondanchor 18 may be advanced over the guide tube 60 and into the hole 94 inthe fibula 92, using the second installation driver tool 70. Asdescribed elsewhere herein, the second component 40 may be secured tothe distal end 72 b of the shaft 72 using one or more detents or otherconnectors 76. To control rotational and other motion of the guide tube60, the back side 54 a of the handle 54 of the first anchor driver tool50 may include a receptacle of grippy material 55 that may be slid overthe proximal end 62 a of the guide tube 60. In addition, the guide tube60 may have features 63 designed to enhance gripping the guide tube 60within the receptacle 55. Alternatively, another tool, e.g. a set ofpliers, a clamp, or other tool (not shown) may be used to hold theproximal end 62 a of the guide tube 60.

Turning to FIG. 11, with the guide tube 60 secured using the back end 54a of the handle 54, the first component 30 of the second anchor 18 mayremain substantially stationary as the second component 40 of the secondanchor 18 is tightened down using the second installation tool 70.Initially, the second component 40 and second installation tool 70 maybe advanced axially over the guide tube 60 without rotation until thesecond component 40 reaches the proximal end 30 a of the first component30. At this point, the second installation tool 70 may be rotated tothread the second component 40 over the first component 30 of the secondanchor 18, thereby slidably engaging the threads 32, 46 (e.g., best seenin FIG. 3). Note that, as the second component 40 of the second anchor18 is tightened down, the head 48 may contact the outer surface of thefibula 92 limiting further advancement of the second component 40.Further rotation causes first component 30 to move proximally, i.e.,disengaging the distal end 30 b of the first component 30 from the firstanchor 10 and retracting it until the flexible link 20 is exposed andreaches its design length, at which point, further tightening of thesecond component 40 of the second anchor 18 reduces the gap between thetwo bones 90, 92. It will be appreciated that the axial location of thesecond anchor 18 may be adjusted as desired to provide a desired gapbetween the bones 90, 92 with rotation of the second component 40causing the first component 30 to move axially within the hole 94 in thefibula and move the fibula 94 closer or further away from the tibia 90.

Turning to FIG. 12, once the implant 10 and bones 90, 92 are positionedas desired, the tools may be removed. For example, the guide tube 60 maybe retracted using the first driver tool 50 after the second component40 of the second anchor 18 has reached its fully-installed state. Toaccomplish this, the user first removes the lock member 86 (not shown,see, e.g., FIGS. 10A and 10B), whereupon the connectors 66 aredisengaged from the pockets 36 in the first component 30 (e.g., as shownin FIGS. 17C-17E), e.g., due to the bias of the connectors 66 to theinward orientation. The guide tube 60 may then be freely withdrawnthrough the shaft 72 of the second installation tool 70, as shown inFIG. 12.

Turning to FIG. 13, the second installation tool 70 may then bedisengaged from the second component 40 and removed. As describedelsewhere herein, the shaft 72 of the second installation tool 70 mayinclude retention features or other connectors 66 on the distal end 72 bthat retain the second component 40 of the second anchor 18 on thesecond installation tool 70 until sufficient force is applied to un-snapit.

FIG. 14 shows the exemplary embodiment of the implant assembly 8 in itsfully-installed state. As shown, in a desired installation, the proximalend 10 a of the first anchor 4 may be substantially flush with thesurface of the cortex of the tibia 90.

FIG. 15 shows an exemplary embodiment of the first driver tool 50 andthe components housed inside it during early installation (e.g., duringthe steps shown in FIGS. 6, 7A, and 7B) in cross-section view. Note theinteraction between the first anchor 10, the first component 30 of thesecond anchor 18, and the first driver tool 50—the external hex of thefirst component 30 of the second anchor 18 spans the internal hexfeatures in the proximal region 12 a of the bore 12 within the firstanchor 10 and the socket within the distal end 52 b of the first drivertool 50. This allows torque applied to the first driver tool 50 by thesurgeon to be transmitted to the first component 30 of the second anchor18. The first component 30 of the second anchor 18 then applies torqueto the first anchor 10 to drive it into the first bone (not shown). Thiscross-sectional view also shows the placement of the guide tube 60 andlock member 86 within the first driver tool 50 during earlyinstallation.

FIG. 16 shows an exemplary embodiment of the first anchor 10, firstdriver tool 50, flexible link 20, first component 30 of the secondanchor 18, and guide tube 60. This view makes the external hex of thefirst component 30 of the second anchor 18 visible, as well as thecorresponding internal hex feature in the distal tip 52 c of the firstdriver tool 50.

While the invention is susceptible to various modifications, andalternative forms, specific examples thereof have been shown in thedrawings and are herein described in detail. It should be understoodthat the invention is not to be limited to the particular forms ormethods disclosed, but to the contrary, the invention is to cover allmodifications, equivalents and alternatives falling within the scope ofthe appended claims.

We claim:
 1. A method for approximating first and second bones relativeto one another, comprising: advancing a first anchor having a firstcomponent into a first bone by applying a force to a driver tool coupledto a first component of a second anchor; disengaging the first componentof the second anchor from the first anchor to expose a flexible linkextending between the first anchor and the first component of the secondanchor; withdrawing the second anchor until the flexible link connectingthe first anchor to the second anchor reaches its designed predeterminedlength, thereby positioning the second anchor in a second bone; affixinga second component of the second anchor to the first component of thesecond anchor such that a head of the second component engages thesecond bone or a bone support on the second bone; and adjusting alocation of the second component along the first component to adjust theapproximation between the first and second bones.
 2. The method of claim1, wherein the first and second bones being approximated are a tibia anda fibula following an injury of the ankle syndesmosis.
 3. The method ofclaim 1, wherein the first component comprises a distal end received ina first socket in the first anchor to couple the first component to thesocket.
 4. The method of claim 3, wherein the first component comprisesa proximal end received in a second socket in a distal end of the drivertool to couple the first component to the driver tool.
 5. The method ofclaim 1, wherein disengaging the first component of the second anchorfrom the first anchor comprises: disengaging a securing feature betweenthe driver tool and the first anchor; and withdrawing the driver toolwhile the first component of the second anchor remains within the secondbone.
 6. The method of claim 5, wherein a guide member extendsproximally from the first component within the driver tool and whereinthe guide member is exposed when the driver tool is withdrawn.
 7. Themethod of claim 6, wherein affixing a second component of the secondanchor to the first component comprises: directing the second componentover the guide member until the second component engages one or morefeatures on the first component; and advancing the second component overthe first component using the one or more features.
 8. The method ofclaim 7, wherein the one or more features comprise external threads onthe first component, wherein the second component comprises internalthreads, and wherein advancing the second component over the firstcomponent comprises threading the second component over the firstcomponent.
 9. The method of claim 7, wherein the second component iscarried on a distal end of an installation tool and wherein theinstallation tool is directed over the guide member to direct the secondcomponent over the guide member.
 10. The method of claim 9, furthercomprising disengaging the installation tool from the second componentafter adjusting the location of the second component along the firstcomponent.
 11. The method of claim 6, wherein a distal end of the guidemember is coupled to the first component, the method further comprising:disengaging the guide member from the first component after adjustingthe location of the second component along the first component; andremoving the guide member.
 12. The method of claim 11, wherein the guidemember distal end is coupled to the first component by a plurality ofdetents on the guide member distal end received in respective pockets inthe first component, and wherein disengaging the guide member comprisesremoving a lock member from the guide member whereupon the detentsautomatically disengage from the respective pockets to allow the guidemember to be removed.
 13. A method for approximating first and secondbones relative to one another, comprising: providing a driver toolincluding a shaft having a distal end, a first anchor, a first componentof a second anchor including a distal end received in a first socket ofthe first anchor, and a proximal end received in a second socket in thedriver tool shaft distal end, and a guide member coupled to the firstcomponent proximal end and extending proximally through the driver toolshaft, the first anchor and first component secured relative to thedriver tool shaft distal end; advancing the first anchor towards a firstbone through a hole in a second bone adjacent the first bone; applyingtorque to the driver tool to direct the first anchor into the firstbone, the torque transferred from the driver tool shaft to the firstanchor via the first component of the second anchor; releasing the firstanchor and first component from the driver tool shaft distal end;withdrawing the driver tool, thereby exposing the guide member;directing a second component of the second anchor over the guide memberto the first component; advancing the second component of the secondanchor over the first component, thereby causing the first componentdistal end to withdraw from the first socket and expose a flexible linkextending between the first anchor and the first component of the secondanchor; advancing the second component further, thereby extending theflexible link to a predetermined length and positioning the secondanchor in the hole in the second bone; engaging a head of the secondcomponent with the second bone or a bone support on the second bone; andadjusting a location of the second component along the first componentto adjust the approximation between the first and second bones.
 14. Themethod of claim 13, wherein the first and second bones beingapproximated are a tibia and a fibula following an injury of the anklesyndesmosis.
 15. The method of claim 13, further comprising: disengagingthe guide member from the first component after adjusting the locationof the second component along the first component; and removing theguide member.
 16. The method of claim 13, wherein the guide memberdistal end is coupled to the first component by a plurality of detentson the guide member distal end received in respective pockets in thefirst component, and wherein disengaging the guide member comprisesremoving a lock member from the guide member whereupon the detentsautomatically disengage from the respective pockets to allow the guidemember to be removed.
 17. The method of claim 13, wherein the secondcomponent is carried on a distal end of an installation tool and whereinthe installation tool is directed over the guide member to direct thesecond component over the guide member.
 18. The method of claim 17,further comprising disengaging the installation tool from the secondcomponent after adjusting the location of the second component along thefirst component.